1. Field of the Invention
The present invention relates to improvement in a device and method for driving a dental hand-piece and more particularly to improvements in the cutting performance of a pneumatically driven dental hand-piece.
2. Prior Art
In prior-art pneumatically driven hand-pieces, the compresed high-velocity fluid (compressed air, hereinafter simply called "air") jetted out of the air outlet is exhausted through the exhaust port after driving the turbine blades, that is, after imparting a driving torque to the blades in the absense of any arrangement to reuse the air. Therefore, the hand-pieces had a drawback in that the driving torque imparted to the blades is smaller than the input amount of kinetic energy, since the air's kinetic energy potential could not be fully utilized.
The present inventors succeeded in overcoming the above-mentioned drawback in their earlier invention for which a patent is pending (Japanese Patent Publication Sho56-42941). The invention not only uses the jet air to drive the confronting blade but also causes a part of the air to act on an adjacent blade in the direction of rotation through an opening provided in the blade for additionally imparting drive torque thereto so that the total amount of torque imparted can be increased when compared with a prior art counterpart. The invention partially reuses the air jetted in the direction of rotation to increase the amount imparted to the torque.